An epoxy resin is widely used mainly in the field of an electric and electronic material parts because of its excellent electric properties.
These electric and electronic material parts are required to have high flame retardancy as represented by a glass epoxy laminated sheet or an IC encapsulating material. However, an epoxy resin alone cannot produce a sufficient effect. Therefore, now, a halogen flame retardant is often being used in combination with this epoxy resin.
Recently, however, the toxicity of organic halogen substances typically represented by dioxin (chlorodibenzodioxin) has become a serious problem and undesirable effects of halogen are exerted on a long-term reliability in IC packages. It is strongly requested to reduce a use amount of halogen or to use a flame retardant using a compound substitutable with halogen or other flame retardant formulations.
Accordingly, a method of addition of a flame retardant such as a phosphorus compound has been under consideration. According to this method, however, flame retardancy is improved, but basic physical properties of a resin such as heat resistance and moisture resistance are undesirably damaged.
In order to eliminate these disadvantages, in JP-A 8-311142 (the term "JP-A" as used herein means an unexamined published Japanese patent application), is proposed the use of a phenol composition modified with a compound having a triazine ring as an epoxy resin hardener.
When this compound is used as a hardener, however, a bond between phenol and a triazine compound is not sufficient. Therefore, the resulting hardened product does not have sufficient characteristics, for example, in heat resistance and moisture resistance, although it shows a flame retardant effect. Thus, the above-described problems cannot be solved.
While, a conventional thermosetting resin composition for a friction material using hexamethylenetetramine as a hardener also has a problem of so-called "noise", which also cannot be solved yet by the above-described technique.
Further, when the compound is used in a paper base laminated sheet, although the resulting paper base laminated sheet shows a flame retardant effect, a problem arises wherein a low temperature punching quality is insufficient.